Psalmopoeus is a genus of the family Theraphosidae containing various species of tarantulas. The genus is native to Central America and South America including the West Indies. These species are believed to be relatively venomous, and research in the venom of P. cambridgei shows it to be similar to capsaicin, the molecule causing irritation in chili peppers. These molecules activate sensory cells to send pain signals to the brain. Genetic engineers are working on blocking the receptors that are activated by these molecules.